Dirasat, Engineering Sciences, Volume 36, No. 2, 2009
Paramecium Caudatum Exhibits Motile Responses Due to
External Electric Stimulation
"Scientific Note"
Abdulrahman A. Alrudainy*
ABSTRACT
My goal is to find out the effects of the electric pulses on the motile behavior of free -swimming Paramecium.
Intracellular microelectrodes and voltage clamp studies have yielded considerable information about the
properties and behaviors of excitable cells. An alternative study is to investigate the use of external electric field
pulses which perturb the membrane potential in a well defined manner. This study describes an investigation of
the technique using the ciliated protozoan Paramecium.
Electrically induced cell movements were recorded using a cine camera and the films were subsequently
analyzed by projecting them onto a digitalizing tablet connected to a computer which then processed the data.
Free swimming specimens of Paramecium responded in a quite characteristic way to stimulation by electric field
pulses in their swimming medium. Cells which happened to be swimming in the direction of the field were
found to increase their swimming speed without reversal, whilst those moving against the field either reversed
completely (swimming backward) or increased their forward swimming velocity to a lesser extent. The
responses showed a marked saturation effect. As the field strength was increased, the response first became
greater but then decreased at higher field strength. There is a relationship between the percentage increase in the
swimming velocity due to electric field pulses and the initial swimming velocity before the pulse.
Keywords: Paramecium Caudatum, Electric Pulses, Swimming Velocity before and after the Pulse.
1. INTRODUCTION
Paramecium has proven to be an exceptionally useful
organism in studies of behavior produced by membrane
excitation because of the wide variety of motile responses
which can be induced. This ciliated protozoa is a single
eukaryotic cell which has an excitable system such as in
nerve cells and muscles. When an electric potential
gradient is established across the medium which contain
the cells, the Paramecium and other ciliates change their
swimming direction towards the cathode, and with
increasing potential gradient the cells exhibit a helical
motion of increasing amplitude while the swimming
speed decreases (Machemer, H. et al., 1977, Machemer,
R. et al.1966, Clark, et al.1991). Normal beating of the
cilia towards the rear of the cell is augmented at anodal
cell surface; reverse beating of cilia, i.e. towards the
* Faculty of Science and Engineering, University of Science
and Technology, Sana'a, Yemen. Received on 24/4/2008
and Accepted for Publication on 11/11/2009.
interior, occurs at cathodal surface. The difference in the
electric sensitivity of the cilia was found in the
Paramecium (Eckert, et al.1970). The anterior half of the
Paramecium is more sensitive and responds to an external
stimulation more strongly than the posterior half.
Like the nerve cell, the imbalance of the ions
concentrations outside and inside the Paramecium causes
an establishing resting potential across the cell
membrane, which ranges from - 20mV to – 40mV
(Naitoh, et al. 1968). The main ions which affect the
resting and active potential of the Paramecium and then
their cilia movement are K + - ions and Ca ++ ions(Yamaguchi, 1960, Okumura, 1962, Machemer,
1976, Naitoh, et al., 1972, Brehm, et al., 1980, Brehm, et
al., 1978, Machemer, 1986, Machemer, 1988, Machemer,
1989, Doughty, 1978, c-І, Doughty, 1978, c-ІІ, Doughty,
1979, Hildebrand, et al., 1976, Hook, et al., 179, Hook, et
al., 1980).
Techniques called voltage clamp, which are based on
clamped potential membrane of the cell at a fixed value
and then the membrane current could be measured and
- 105 -
© 2009 DAR Publishers/University of Jordan. All Rights Reserved.
Paramecium Caudatum…
Abdulrahman A. Alrudainy
analyzed, were successfully applied to Paramecium for
studying the electrophysiological events and their
mechanisms which produce stimulation of the organisms
(Oertel, et al., 1977, Eckert, et al., 1979, Ogura, 1980).
When the resting potential of the membrane was
depolarized it caused the cilia movement reversed. This
reversing in cilia beating was attributed to calcium
hypothesis, which was based on supposing that all
reversals in ciliary beating were due to the influx of Ca
++ ions from the external medium to the interior of the
cell and which was regulated by membrane permeability
to Ca ++ (Eckert, et al., 1970, Naitah, et al., 1972, Eckert,
1972, Machemer, 1973).
Fig. 1. Circuit diagram of pulsing control unit
Application of pulse generator press switch energizes the L.E.D. indicator lamp at the same instant as the transistor is
switched on to establish the electric field in the trough. The image of the L.E.D. is projected onto the cine film using
camera-arm attachment. Values of resistances R1, R2, and R3 are 56 kΩ, 3.3 kΩ, and 6.8 kΩ, respectively; the capacitor is
1.0 µF.
Fig. 2. Circuit diagram of system used to measure the electric current flow through the suspension of
paramecia during an electric pulse
- 106 -
Dirasat, Engineering Sciences, Volume 36, No. 2, 2009
The membrane of Paramecium behaves as an ohmic
resistance with parallel capacitance in response to current
pulses applied to the membrane producing an electronic
potential shift of several millivolts (Naitoh, et al., 1974).
Stronger hyperpolarization produced some delayed
anomalous rectification appearing as a decrease in the
potential drop produced by the current passed across the
membrane. A strong depolarization current produced an
inflexion in the rising phase seeming as two peaks (Naitoh,
et al., 1972). The first one represents the electrotonic
potential component and the second peak is regenerative
response component. After reaching its peak, the potential
drops to a lower level with a damped oscillation.
The freshwater ciliate Paramecium uses gravity as an
environmental stimulus for its spatial orientation
(gravitaxis) and for the control of its swimming velocity
(gravikinesis). Though Paramecium is heavier than water,
it is able to swim against the direction of gravity
(negative gravitaxis). Measurements of Paramecium
antagonize sedimentation by an active speed regulation,
resulting in a faster swimming velocity than expected by
calculations (Hemmersbach, et al., 1991, Machemer, et
al., 1992, Braucker, et al., 1998). In the absence of other
stimuli, gravitaxis and gravikinesis help the cells to move
and stay in suitable habitats. Weightlessness, light,
chemicals, and other stimuli will affect the swimming
behavior of the Paramecium (Hemmersbach, 1979,
Hemmersbach, et al., 1993, Colmbetti, 1990).
2. MATERIALS AND METHODS
In this study, a Paramecium Caudatum was cultured
in the laboratory by growth hay infusion and prepared for
ensuing experimental work. All organisms were grown at
temperatures within range of 21 oC – 23 oC.
Paramecia were harvested and concentrated for
experimental work in the following way: cells in hay
infusion were pipetted into a narrow-necked vessel and then
diluted with standard solution consisting of distilled water
that containing 1mmol.dm – 3 CaCl2, 2mmol.dm – 3 KCl, and
1mmol.dm– 3 Tris (hydroxymethyl amino methane amino
hydrochloride) buffer adjusted to pH 7.0 – 7.2.
Due to their negative geotaxis, the paramecia tend to
swim upwards and accumulate in the narrow neck of the
containing vessel, forming a very concentrated cell
suspension. These cells were collected and transferred by
pipette to the Perspex trough together with amount of
standard solution. The trough was 6.0cm long, 1.0cm
wide and 0.5cm deep. Two stainless steel electrodes were
established at each end of the trough.
The pulses, which were applied to the paramecia
swimming around the trough, were produced by the circuit
shown in Fig. (1). A pulse generator (Type 233, G & M
Bradley Ltd. London) was connected between the emitter
and the base of the transistor. With the transistor “off” the
collector was held at high positive potential. When the
button of the pulse generator was pressed the transistor was
switched on and a potential drop occurred at the collector
of the transistor, establishing a potential gradient across the
trough for a duration of the pulse. As a result of existence
of polarization charges at the electrodes, one can conclude
that it cannot simply be assumed that the electric field in
the conducting medium in the trough is given by the
measured potential difference across the electrodes divided
by the electrodes separation.
So, the actual electric field inside the trough was
calculated by measuring the current flow through the
trough during the pulse; knowing the conductivity of the
solution, the electric field in the medium could then be
obtained.
The current through the trough was not measured
directly because of difficulty in observing the current
pulse of a short duration in high voltage line using an
oscilloscope. Instead, a variable resistance R, was chosen
and connected across the output of the pulsing unit
(Fig.2). A long pulse of about 3.0s duration was applied
and the current through the resistor was determined using
a milliammeter. As the pulse was applied, there was a
potential drop across the 3.3kΩ resistor in the pulsing
control unit, Fig.(1), which was displayed on the screen
of the storage oscilloscope. A series of readings of the
current and the voltage were then obtained for various
values of the resistance R. The previous procedure was
repeated with different values of voltage supply. This
procedure was necessary because the internal resistance
of the power supply depends on the open circuit voltage
which it produces. A series of calibration graphs of the
relationship between the current I vs. potential drop, ∆V,
for each voltage range on power supply were constructed.
Thus, the current flow through the trough during any
pulse can be obtained from the calibration graphs from
the value of V determined during the pulse. This
measurement, together with the experimentally
determined value of the resistivity of the standard
solution in the trough permitted the electric field in the
trough during the pulse to be calculated.
- 107 -
Paramecium Caudatum…
Abdulrahman A. Alrudainy
(D and E are the two stainless steel electrodes, T is the glass tube R1, R2, and R3 are three variable resistances).
Fig.3. The circuit diagram of the system used to measure the resistivity of the paramecia suspension
The resistivity of the culture solution was determined
by using Wheatstone bridge method. Two fixed stainless
steel electrodes were placed at either end of a long glass
tube of internal diameter 1.1cm which could be
exchanged for other tubes of varying length, Fig. (3). An
alternating voltage with frequency of about 300Hz was
established across the bridge. The signal picked up across
the bridge was displayed on the oscilloscope. Three
calibrated "dial" resistances were used together with the
tube containing culture medium as a fourth. Two of three
variable resistances were fixed and the third was varied
until a minimum oscilloscope signal was obtained. At
balance the relation between the resistances in the arms of
the bridge is;
R1 / R2 = R3 / RT and so
RT = R2 R3 / R1
A shorter length of tube, T, was then selected and the
experiment repeated. So, the difference between the two
previous measurements of RT, is represented the value of
the resistance R, of a length L, of the culture medium.
The diameter of tube T, was measured by vernier caliper.
The resistivity, ρ, of the medium was calculated by:
R=ρL/A
and so
ρ=RA/L
where A, is the cross-sectional area of the medium in
trough. The resistance r, of the medium in trough used in
the experiments was then calculated, when filled to
defined level. Therefore the actual potential difference
inside the trough is given by:
V=I.r
where I is the current flow through the medium in
trough.
- 108 -
Table (1) shows the p.d. applied by the voltage supply
and the calculated p.d. inside the trough. The implication
of these results is that less of the applied voltage across
the two electrode – electrolyte interfaces in the trough. A
low power stereomicroscope (Type IV, Carl Zeiss) with x
10 eyepieces and 0.8 – 4 x zoom objective was used to
observed the swimming paramecia. This system provided
a dark ground image and allowed a working distance of
84 mm. Illumination of the trough (containing cells with
their medium), obtained from projector lamp, was
incident on the inclined surface of mirror then reflected to
shine into the trough.
Table 1. Comparison between applied and calculated
p.d. across the trough.
Applied p.d.
Calculated p.d.
(in volts)
(in volts)
150
90
200
250
120
180
300
350
400
450
215
253
290
342
The paramecia were photographed using a Vinten
MK3 cine camera at 8 frames per second. The camera
was equipped with watching eyepiece attachment which
enable the trough to be viewed during filming. A
focusing eyepiece was used to adjust the microscope and
camera before being replaced by the film magazine.
Dirasat, Engineering Sciences, Volume 36, No. 2, 2009
Fig.4. L.E.D. Control system R1, R2, R3, and R4 are 1 MΩ, 680 Ω, 10 kΩ, and 680 Ω respectively.
R3 is potentiometer; C is 2.2 µF
Fig. 5. The pre-pulse swimming direction, θo, comparing with the change in swimming direction, ∆θ, after the
pulse. (The points represent cell directions for all pulses used in the experiments. ♦ 8-19 cells, and ● 7-4 cells)
- 109 -
Paramecium Caudatum…
Abdulrahman A. Alrudainy
Fig.6. The percentage increase in forward swimming speed compared with initial speed for cathodal cells,
following a pulse of 30 V cm – 1 and 0.8 ms duration
The film was analyzed using analyzing film projector.
Individual frames were projected forwards and
backwards and examined for as long as required. The
film frames were projected onto pid pad tablet. The pid
pad converts graphics information into digital form
suitable for entry into computer. "pulsed cycle" button
was initiated a pulse, a red miniature light emitting diode
(L.E.D), connected to a time delay circuit Fig. (4), and
mounted within a tube connected to further subsidiary
opening in watching eyepiece, was illuminated. This was
positioned so that it could be seen in the corner of the
film frame, thus providing an indication of the instant of
the onset of the pulse. The timer circuit enable the L.E.D
to remain on after the pulse in the trough had ceased, and
was necessary for the short pulse to ensure that the
activated L.E.D was recorded on the film.
A computer program was designed to analyze the cell
movement before and after applying the electric pulse.
The program calculates the swimming velocity and the
swimming direction with respect to instantaneous electric
field direction. It was calculated the average swimming
velocity before and after the pulse, and also it was
- 110 -
distinguished between the moving forward and the
moving backward cases.
3. EXPERIMENTAL RESULTS
Two principal types of responses were observed
depending on whether the cell was swimming toward the
anode or cathode before the pulse.
Cell Movement Toward Cathode Before The pulse
All organisms which were observed in this class of
experiments were initially swimming towards the cathode
within the range of 0 o – 30 o with respect to the electric
field. The most striking observation is that in no
circumstances do cell reverse (swimming backward)
following the electric field stimulation. Instead, they
immediately increases their forward swimming velocity
by an amount governed both by the pulse strength and the
prepulse swimming velocity.
No consistence changes in swimming direction seems
occurred after the electric field pulse (Fig.5). Most cells,
81% change their swimming direction within the range of
0 o – 20 o with respect to the electric field direction.
Dirasat, Engineering Sciences, Volume 36, No. 2, 2009
By trial and error, it was discovered that the best
linear relationship between the initial velocity and the
increase in velocity was obtained by plotting the
percentage increase in forward swimming velocity
against the prepulse velocity for a given pulse (Fig.6),
which it is shown that the faster the cells are swimming
before the pulse, the smaller the resulting percentage
increase in swimming velocity.
Table 2. (a) The relationship between the initial velocity (vo in mm s – 1) and the percentage in the velocity (∆v %)
after the pulse, for organisms swimming towards the cathode before the pulse.
N is the total number of organisms observed, vm is the vo – axis intercept in mm s – 1,C.C. is the correlation coefficient, E is
the electric field in V cm – 1, and T is the pulse duration in ms.
60% of C.C. values are significant at 5% level.
E.
V/c
m
V/c
m
15
20
30
35.8
42.2
48.3
N
Vm
C.C.
N
Vm
8
10
10
12
10
11
2.87
2.47
1.91
2.05
1.89
2.02
-0.477
- 0.395
- 0.600
- 0.961
- 0.918
- 0.976
10
9
14
11
10
9
2.58
2.00
1.71
2.01
1.96
1.88
57
11
2.12
- 0.839
T = 0.2 ms
T = 0.4 ms
T = 0.6 ms
C.C.
N
Vm
T = 0.8 ms
T = 1.0 ms
T = 1.2 ms
C.C.
N
Vm
C.C.
N
Vm
C.C.
N
Vm
C.C.
- 0.134 10 2.11
- 0.975 8 1.72
- 0.900 9 1.73
- 0.875 10 2.12
- 0.933 10 1.96
- 0.924 9 1.99
- 0.720
- 0.955
- 0.935
- 0.888
- 0.859
- 0.889
9
12
10
11
10
12
2.57
2.06
1.62
1.97
2.23
2.16
- 0.886
- 0.779
- 0.804
- 0.840
- 0.903
- 0.789
9
13
13
10
11
10
1.69
2.00
1.93
1.91
1.82
1.69
- 0.916
- 0.918
- 0.837
- 0.890
- 0.913
- 0.918
10
11
14
10
10
10
1.88
1.91
1.83
1.75
1.98
1.78
- 0.897
- 0.887
- 0.894
- 0.878
- 0.736
- 0.909
10 1.72 - 0.882 13 1.71
- 0.881
8
2.42
- 0.917
9
2.41 - 0.910
10
1.97 - 0.616
b) Gradients of regression lines (∆v % / mm s – 1) for each electric field pulse combination
T
0.2 ms
0.4 ms
0.6 ms
0.8 ms
1.0 ms
1.2 ms
15
+3
-2
- 48
- 30
- 69
- 88
20
- 5
- 75
- 130
- 86
- 81
- 99
30
- 54
- 132
- 134
- 177
- 79
- 103
35.8
- 95
- 90
- 82
- 108
- 114
- 136
42.2
- 122
- 108
- 92
- 72
- 154
- 83
48.3
- 87
- 109
- 100
- 75
- 140
- 105
57
- 60
- 123
- 141
- 71
- 75
- 91
E
Correlation coefficients determined between initial
and percentage velocity and velocity increase for each
pulse investigated are shown in Table (2). in most cases,
the correlation coefficient is statically significant at 5%
significance level (t-distribution). The regression lines are
characterized by two parameters: the slope and the
intercept on the velocity axis, Vm, (Table (2.b) and
(2.b)). The slope is small for weak pulses, increased to
about 150% / mm s – 1 for strong pulses and then remain
constant over the range of electric field strength and pulse
durations used in the experiments. Most of the values of
the intercept on the initial swimming velocity-axis seems
to be on average in a range of about 1.8 – 2.1 mm s – 1,
Table (2.a). This is particularly interesting since it implies
that the electric response depends on some intracellular
parameter which also governs the normal unstimulated
swimming velocity in the organism.
Cell Movement Towards Anode Before Pulse
When the organisms swim toward the anode (i.e.
within a range of 150o – 180o to the electric field
direction) and are subjected to an electric pulse, the most
obvious response is that a certain proportion of them
reverse. After a certain time (termed here the reversing
time) normal forward swimming is resumed.
- 111 -
Paramecium Caudatum…
Abdulrahman A. Alrudainy
Fig.7. The relationship between swimming direction before the pulse and the change in swimming direction after
the pulse for cells initially towards the anode.(Each symbol represent a single cell).
Table 3. The effect of pulses of varying strength and duration on percentage
of reversing organisms
E is the electric field V cm–1, T is the pulse duration in ms, N is the total number of cells observed, NR is the
number of cells reversing for a given pulse.
E
V/cm
T pulse duration, ms
0.2
0.4
0.6
0.8
1.0
1.2
N
NR
N
NR
N
NR
N
NR
N
NR
N
NR
15
7
0
11
0
9
0
9
0
8
1
10
3
20
7
0
10
0
15
4
11
11
11
9
12
9
30
8
0
14
4
14
11
10
9
15
14
14
6
35.8
14
4
15
12
11
9
12
9
11
10
12
0
42.2
14
8
13
11
10
3
10
1
13
2
11
0
48.3
17
5
11
2
7
0
11
2
9
0
13
0
57
14
5
13
2
15
0
10
0
9
0
10
0
Reversal is usually accompanied by a big change in
swimming direction (Fig.7). Most of the cells (about
84%) change their swimming direction by more than 60 o.
So, there is a marked tendency for them to turn towards
the cathode following reversal.
The percentage of cells reversing depends upon the
- 112 -
electric field strength and pulse duration (Table 3). As the
strength of the electric stimulus is increased, the
percentage of the organisms reversing first increases and
then decreases. For each pulse length there appears to be
some optimum field strength which maximizes the
probability of reversal , see Fig. (8).
Dirasat, Engineering Sciences, Volume 36, No. 2, 2009
Fig.8. The relationship between percentage of reversing cells and the electric field strength.
Pulses were of 1.0 ms duration and varying strengths (amplitudes). Each point on the graph was measured from
8-15 organism.
Table 4. Effect of electric field strength on the mean reversing time (in seconds)
[the figures in the table represent the mean reversing time ± S. D.]
E
T pulse duration in ms
V cm - 1
0.2
0.4
0.6
0.8
1.0
1.2
15
0
0
0
0
0.5
1.3 ± 0.8
20
0
0
0.8 ± 0.8
1.4 ± 1.1
1.6 ± 0.7
1.7 ± 0.9
30
0
1.2 ± 0.8
1.1 ± 0.5
2.1 ± 0.6
1.3 ± 0.8
1.0 ± 0.6
35.8
0.6 ± 0.6
1.6 ± 0.9
1.1 ± 0.5
0.8 ± 0.6
1.1 ± 0.9
0
42.3
1.3 ± 0.8
1.4 ± 0.5
1.6 ± 1.0
0.4
1.1 ± 0.6
0
48.3
1.4 ± 0.8
1.6 ± 0.9
0
1.1 ± 0.7
0
0
57
0.9 ± 0.7
1.6 ± 0.4
0
0
0
0
In most cases, there is an increase in the forward
swimming velocity after the pulse, both for nonreversing
and for reversing organisms, once normal forward
swimming is resumed. About 60% of the values of the
correlation coefficient between the initial (prepulse)
swimming velocity for both nonreversing and reversing
organisms are statically significant at 5% significance
level of t-distribution. The mean reversing time for those
paramecia which do reverse after a pulse is shown in
Table (4). The reversing time clearly increases to a peak
value and then remain at a constant value (plateau).It is
found, there is a linear relationship between the
percentage reversing and mean reversing time (Fig.9) for
various pulse amplitudes and duration combination. The
regression line of this relation has a correlation
coefficient value of 0.844 which is significant at 5%.
significance level of t-distribution. Within the statistical
errors, the percentage reversal may be proportional to the
mean reversal time. This suggests that a common
mechanism may be operating. A small stimuli may not
sufficient to cause any reversal, while the larger stimuli
causes first reversal onset and then increasingly large
reversal time
- 113 -
Paramecium Caudatum…
Abdulrahman A. Alrudainy
Table 5. Relationship between the initial swimming velocity Vo and the change
in swimming velocity ∆v after the pulse.
T pulse duration in ms
0.2
E
V cm
-1
m
0.4
C.C.
m
0.6
C.C.
0.8
m
C.C.
m
1.0
C.C.
1.2
m
C.C.
m
C.C.
*
-0.674
-0.631
-0.833
-0.839*
15
-0.012
- 0.087 -
-0.022
-0.096
-0.180
-0.211
-0.473
-0.826
20
-0.018
- 0.093
-0.526
-0.322
-0.973
-0.574
-0.667
-0.633*
-0.665
-0.849*
-0.901
-0.942*
30
-0.044
- 0.215
-0.868
-0.957*
-0.986
-0.922*
-0.700
-0.449
-0.409
-0.504
-1.062
-0.890*
35.8
-0.643
- 0.724*
-0.761
-0.746*
-0.993
-0.865*
-0.931
-0.645
-0.809
-0.859*
-0.613
-0.757*
42.2
-0.851
- 0.913*
-0.750
-0.751*
-0.826
-0.733*
-0.839
-0.850*
-0.134
-0.109
-0.265
-0.273
*
-0.658
-0.508
-0.158
-0.187
-0.627
-0.685*
-0.934
-0.850*
-0.634
-0.539
-0.908
-0.907*
-0.738
-0.907*
-0.532
-0.468
48.3
-0.854
- 0.987*
-1.159
-0.838
57
-0.586
- 0.702*
-0.885
-0.716*
4. DISCUSSION
The work presented here has shown that a brief
application of an electric field with intensities ranging
from 15 V cm – 1 to 57 V cm – 1 for periods of 0.2 ms is
capable of producing motile responses in freely
swimming specimens of Paramecium. When a steady
electric current is established in a medium containing
Paramecium, the organisms turn and swim towards
the cathode. The present study shows that most
organisms swimming towards the anode when the electric
pulse is applied respond by momentarily swimming
backward (reversing) towards the cathode. In contrast,
those organisms swimming towards the cathode prior to
the pulse (electric field) respond to it by increasing their
forward swimming speed. These results indicate that the
posterior part of the cell has an important role in
governing the cell's responses due to electric field. As the
cell swims towards the anode prepulse, it seems likely
that the membrane potential of the anterior part is
hyperpolarized while the posterior part is depolarized as
it is facing the cathode, due to an electric pulse. Then, for
some reason, the depolarization effect spreads over the
whole cell resulting in reversal cilia beating and
consequently causing a reversal swimming. In contrast,
hyperpolarization seems to spread over the whole cell
surface when the posterior part lies towards the anode
before the pulse, resulting an increase in frequency of the
normal beating of the cilia which in turn lead to an
increase in the forward swimming velocity of the cell
after the pulse. Studying Fig.(6), shows that the cell
which swims slowly towards the cathode before the pulse
will gain a greater percentage increase in its forward
swimming velocity due to a given pulse than the faster
one. If it is assumed that any pulse will simply make the
- 114 -
velocities of the cell population increase to the same
maximum velocity, then
∆v = vmax - vo
and
∆v / vo = vmax / vo - 1
where vo is the initial velocity (prepulse) in mm s – 1,
and vmax is the maximum velocity due to any pulse in
mms-1.
So, plots of vmax against vo, and ∆v against vo should
be straight lines. But, the experimental data shows that
there is no linear relationship between the swimming
velocity before and after the pulse, which means that each
cell among the population swims after the pulse with
different velocity. It is found that only 60% of the
correlation coefficients of the linear regression for the
relationship between ∆v and vo are significant at level of
5%, table (5), and this means that the relationship is not
straight line for many pulses.
The data in this table were produced from those cells
swimming towards the cathode before the pulse. m is the
slope of the relationship, ∆v vs. vo. C.C. is the correlation
coefficient of the linear regression.(*) is a symbol means
that the correlation coefficient is significant at 5% level
of t – distribution. The number of the cells at each pulse
is the same as in Table (2).
These results give a contrary proposition to the above
assumption and equation, and also show that the
swimming velocity of the paramecia is not dependent on
the strength of the electric pulse. The level of the
intraciliary calcium concentration before and after the
pulse which has an ability to control the swimming
velocity of the cell, might be considered as another
assumption to explain the swimming velocity before and
after the pulse. There is no other investigated biological
system which exhibits similar behaviors, and this
investigation seems to be first attempt so far, to the
Dirasat, Engineering Sciences, Volume 36, No. 2, 2009
swimming velocity to electric pulse. It is clear that the
electric fields employed perturbed some fundamental
aspect of the cell motility mechanism, but from the data
presented in this work, it is not possible to draw affirm
explanation on the basis of the mechanism itself.
However, it is possible to use a physiological model to
give a reliable interpretation of the experimental results
presented here, and this is what will be done in the
following work.
Many researchers are used galvanotaxis (swimming
velocity response to electric stimulus) of Paramecium
cells to utilize them as microrobots. This done by control
the microorganisms as smart microscale robots for a
variety of applications (Fearing, 1991, Ogaw, et al., 2005,
Takahashi, et al., 2006). Cell motility studies, can be
provided an understanding how the cell be able to convert
the stored chemical energy within it to mechanical one,
and understanding how small biological forces generated
at the molecular level are marshaled and organized for
large scale cellular or organismal movements(Daniel, et
al., 2004).
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‫‪Dirasat, Engineering Sciences, Volume 36, No. 2, 2009‬‬
‫ﺒﺭﺍﻤﺴﻴﻭﻡ ﻜﺎﺩﺘﻭﻡ ﻴﻘﻭﻡ ﺒﺎﺴﺘﺠﺎﺒﺎﺕ ﺤﺭﻜﻴﺔ ﺒﻔﻌل ﺘﺤﻔﻴﺯ ﻜﻬﺭﺒﺎﺌﻲ ﺨﺎﺭﺠﻲ‬
‫ﻋﺒﺩ ﺍﻟﺭﺤﻤﻥ ﺍﻟﺭﺩﻴﻨﻲ*‬
‫ﻤﻠﺨﺹ‬
‫ﺍﻟﺩﺭﺍﺴﺎﺕ ﺍﻟﺘﻲ ﺘﺴﺘﺨﺩﻡ ﻁﺭﻴﻘﺔ ﻏﺭﺯ ﺍﻷﻗﻁﺎﺏ ﺍﻟﻜﻬﺭﺒﺎﺌﻴﺔ ﺍﻟﺩﻗﻴﻘﺔ ﺒﻴﻥ ﺍﻟﺨﻼﻴﺎ ﺍﻟﺤﻴﺔ ﻭﻜﺫﻟﻙ ﻁﺭﻴﻘﺔ ﺘﺜﺒﻴﺕ ﺍﻟﺠﻬﺩ ﺍﻟﻜﻬﺭﺒﺎﺌﻲ‬
‫ﻟﻠﺨﻠﻴﺔ ﺍﻟﺤﻴﺔ‪ ،‬ﻗﺩﻤﺕ ﻤﻌﻠﻭﻤﺎﺕ ﻗﻴﻤﺔ ﻟﺘﺼﺭﻓﺎﺕ ﺍﻟﺨﻼﻴﺎ ﺍﻟﺴﺭﻴﻌﺔ ﺍﻻﻫﺘﻴﺎﺝ‪ .‬ﻫﻨﺎﻟﻙ ﻁﺭﻴﻘﺔ ﺒﺩﻴﻠﺔ ﻟﺩﺭﺍﺴﺔ ﻫﺫﻩ ﺍﻟﺘﺼﺭﻓﺎﺕ‪ ،‬ﻭﺫﻟﻙ ﻋﻥ‬
‫ﻁﺭﻴﻕ ﺍﺴﺘﺨﺩﺍﻡ ﻨﺒﻀﺎﺕ ﻟﻠﻤﺠﺎل ﺍﻟﻜﻬﺭﺒﺎﺌﻲ ﺍﻟﺨﺎﺭﺠﻲ ﻭﺍﻟﺘﻲ ﺘﺴﺒﺏ ﺍﻀﻁﺭﺍﺒﹰﺎ ﻓﻲ ﺍﻟﺠﻬﺩ ﺍﻟﻜﻬﺭﺒﺎﺌﻲ ﻟﻐﺸﺎﺀ ﺍﻟﺨﻠﻴﺔ ﺍﻟﺤﻴﺔ‪ .‬ﻫﺫﻩ‬
‫ﺍﻟﺩﺭﺍﺴﺔ ﺘﺼﻑ ﺘﻘﻨﻴﺔ ﺍﻟﺒﺤﺙ ﺍﻟﺫﻱ ﻴﺴﺘﺨﺩﻡ ﺍﻟﺒﺭﺍﻤﺴﻴﻭﻡ ‪ Paramecium‬ﺍﻟﻤﻐﻁﻰ ﺒﺎﻷﻫﺩﺍﺏ‪.‬‬
‫ﺘﺴﺠل ﺤﺭﻜﺎﺕ ﺍﻟﺨﻠﻴﺔ ﻗﺒل ﺍﻟﺘﺤﻔﻴﺯ ﺍﻟﻜﻬﺭﺒﺎﺌﻲ ﻭﺒﻌﺩﻩ ﺒﻭﺍﺴﻁﺔ ﻜﺎﻤﻴﺭﺍ ﺴﻴﻨﻤﺎﺌﻴﺔ‪ ،‬ﻭﻤﻥ ﺜﻡ ﻋﺭﺽ ﺍﻟﻔﻠﻡ ﻋﻠﻰ ﻟﻭﺡ ﻴﻘﻭﻡ ﺒﺘﺤﻭﻴل‬
‫ﺍﻟﺼﻭﺭﺓ ﺇﻟﻰ ﺼﻭﺭﺓ ﺭﻗﻤﻴﺔ ﻭﻤﻥ ﺜﻡ ﺇﺩﺨﺎﻟﻬﺎ ﺇﻟﻰ ﺍﻟﺤﺎﺴﻭﺏ ﺍﻟﻤﺭﺒﻭﻁ ﻤﻊ ﺍﻟﻠﻭﺡ ﻟﻠﻘﻴﺎﻡ ﺒﺘﺤﻠﻴل ﺍﻟﺼﻭﺭﺓ ﻤﻌﻠﻭﻤﺎﺘﻴﹰﺎ‪.‬‬
‫ﻤﺠﻤﻭﻋﺔ ﺍﻟﺒﺭﺍﻤﺴﻴﻭﻡ ﺍﻟﺘﻲ ﺘﺴﺒﺢ ﺒﺸﻜل ﻜﻠﻲ ﺇﻟﻰ ﺍﻟﺨﻠﻑ ﺃﻭ ﺘﺯﻴﺩ ﻤﻥ ﺴﺭﻋﺔ ﺴﺒﺎﺤﺘﻬﺎ ﺍﻷﻤﺎﻤﻴﺔ ﻟﻔﺘﺭﺓ ﻗﺼﻴﺭﺓ‪.‬‬
‫ﺍﻟﺨﻼﻴﺎ ﺘﺯﻴﺩ ﻤﻥ ﺍﺴﺘﺠﺎﺒﺘﻬﺎ ﻤﻊ ﺯﻴﺎﺩﺓ ﺸﺩﺓ ﺍﻟﻤﺠﺎل ﺍﻟﻜﻬﺭﺒﺎﺌﻲ ﺒﺎﺩﺉ ﺍﻷﻤﺭ‪ ،‬ﻭﻤﻥ ﺜﻡ ﺘﺘﻨﺎﻗﺹ ﻫﺫﻩ ﺍﻻﺴﺘﺠﺎﺒﺔ ﻤﻊ ﺸﺩﺓ ﺍﻟﻤﺠﺎل‬
‫ﺍﻟﻜﺒﻴﺭﺓ‪ .‬ﻫﻨﺎﻟﻙ ﻋﻼﻗﺔ ﻤﺒﺎﺸﺭﺓ ﺒﻴﻥ ﺍﻟﺯﻴﺎﺩﺓ ﺍﻟﻤﺌﻭﻴﺔ ﻟﺴﺭﻋﺔ ﺍﻟﺴﺒﺎﺤﺔ ﻨﺘﻴﺠﺔ ﺍﻟﻨﺒﻀﺎﺕ ﺍﻟﻜﻬﺭﺒﺎﺌﻴﺔ ﻭﺍﻟﺴﺭﻋﺔ ﺍﻻﺒﺘﺩﺍﺌﻴﺔ ﻗﺒل ﺍﻟﻨﺒﻀﺔ‪.‬‬
‫ﺍﻟﻜﻠﻤﺎﺕ ﺍﻟﺩﺍﻟﺔ‪ :‬ﺒﺭﺍﻤﺴﻴﻭﻡ ﻜﺎﺩﺘﻭﻡ‪ ،‬ﻨﺒﻀﺔ ﻜﻬﺭﺒﺎﺌﻴﺔ‪ ،‬ﺍﻟﺴﺭﻋﺔ ﻟﻠﺴﺒﺎﺤﺔ ﻗﺒل ﺍﻟﻨﺒﻀﺔ ﺍﻟﻜﻬﺭﺒﺎﺌﻴﺔ ﻭﺒﻌﺩﻫﺎ‪.‬‬
‫________________________________________________‬
‫* ﻜﻠﻴﺔ ﺍﻟﻌﻠﻭﻡ ﻭﺍﻟﻬﻨﺩﺴﺔ‪ ،‬ﺠﺎﻤﻌﺔ ﺍﻟﻌﻠﻭﻡ ﻭﺍﻟﺘﻜﻨﻭﻟﻭﺠﻴﺎ‪ ،‬ﺼﻨﻌﺎﺀ‪ ،‬ﺍﻟﻴﻤﻥ‪ .‬ﺘﺎﺭﻴﺦ ﺍﺴﺘﻼﻡ ﺍﻟﺒﺤﺙ ‪ ،2008/4/24‬ﻭﺘﺎﺭﻴﺦ ﻗﺒﻭﻟﻪ‬
‫‪.2009/11/11‬‬
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